The present invention proposes an Inner Cushion (IC) for helmets having a shock absorbing padding consisting of either an inorganic (i.e. containing silica aerogel) or organic (i.e. containing carbon aerogel, an RF aerogel, a viscoelastic polymer foam, etc.) composite foam, mixed with other Organic or Mineral Foam and an external metal or metal-polymer foil protector in both sides.
The majority of helmet manufacturers utilize EPS (Expanded Polystyrene) or EPP (Expanded Polypropylene) materials for absorbing impacts. Those materials provide a good kinematic behavior in the head deceleration, but from the dynamic point of view, the stored energy in the elastic material will be returned to the deforming agent, i.e. the head, producing further damages to the brain.
Two common causes of brain damage are head wounds and severe blows to the head. Head wounds describe wounds which actually extend into the brain itself, such as might be the case if a person was shot in the head or if they suffered a crush in part of the skull in an accident. If the skull becomes broken then the brain is vulnerable to direct damage, this is an open head injury. Alternatively, the brain may become damaged even if the skull remains intact if the head receives a very severe blowxe2x80x94a closed head injury. In such cases the damage can be both from the direct strike against the inside of the skull (coup) or from the resulting forces of rotation which cause the brain to strike against the skull at the opposite side of the head (countercoup). These two types of injuries constitute the two most common causes of brain damage in young adults (often resulting from car or motorbike accidents). A further complication of closed head injury is the fact that local neurons tend to develop edema where neurons close to the site of injury swell, retain fluid and become less excitable.
A head impact, depending on the deceleration, on the shape of the impacting agent or the presence of a protecting helmet, can follow with a perforation, or not, of the skull. Thus, there can be immediate damage to the head by a cranial fracture and direct brain injures. But, on the other hand, there are many damaging effects produced by further accelerations undergone by the brain until the whole body becomes completely stopped. These subsequent translations, rotations and distentions produce tears, slippings, squashings and other destroying injuries in the brain. These injuries subsequently can give rise to vein squashings, cellular damage, hemorrhages and ischemia. The final edema generates in a few days a brain necrosis in the surrounding area of the first impact, even with the best treatments (i.e. citicoline). It""s the opinion of the best specialists on craneo-encephalic traumatisms that brain damage due to xe2x80x98bounce effectsxe2x80x99 are even more important than those ones produced by the first impact. It should be pointed out that preserving any small part of the brain from damage implies a considerable improvement in the quality of life for the accident victims. We should not forget the huge social and sanitary costs of treating and maintaining persons with reduced brain activity.
The present invention proposes the utilization of composite foams, as those made with aerogels, in helmets to take up (better than store and release) kinetic energy and eliminate the xe2x80x98bounce back on headxe2x80x99 effect. These foams, sandwiched between protecting foils, constitute the core of Inner Cushions which fill the gap between the head to be protected and the external outer shell.
It""s the purpose of this invention to provide a method to absorb the impact energy by using a stiff inner cushion consisting mainly of a mechanically inelastic material.
The absorbing impact energy materials referred in this invention use two different mechanisms to convert kinetic energy into heat:
a) Crushing of the structure of the material, i.e. silica aerogel is like foamed glass, the collapse of the dentritic structure surrounding pores needs lot of energy, finally converted in heating the crushed material.
b) Diffuse air in the intricate network of pores, i.e. silica aerogels contain an open network of pores in the mesopore range, the fast diffusion of air through the pore network during the collapsing of the material generates turbulences in the microscopic scale converting kinetic energy in heated air.
It""s also a purpose of this invention to protect the filling materials of the cushion by two covering foils made either by a metal, i.e. aluminum, or a metal-polymer film, i.e. mylar.
It""s also a purpose of this invention to provide possible methods to establish the integrity of the stiff inner cushion, i.e. testing the electrical capacitance of the protecting foils, which is related with the average distance between the foils and the dielectric performance of the cushion containing material.
It""s also a purpose of this invention to provide a fire-resisting inner padding, which could protect even at temperatures as high as 500xc2x0 F. with a suitable flame resistance lining material.
The purpose of this invention is to provide inner cushions for helmets with-lower or equal weight than those existing in the market.
From the medical point of view, the purpose of this invention is to improve the protecting performance of the existing helmet cushions, mainly made with expanded polystyrene and expanded polypropylene, by using composite foam materials as fillers which finally reduce the effects of bounce back on the head such as diffuse axonal injuries, hypoxia, ischemia, blood vessels shearing and other damaging brain effects derived from head impacts.
The purpose of this invention is to improve the coma values in the Glasgow scale of head injured victims and allow a better quality of life in the post-traumatic period.
The purpose of this invention is also to adapt the mechanical properties of the cushion and its density by varying the materials composition depending on the expected application of the helmet, in particular in relationship with the maximum deceleration envisaged, i.e. bikes, skates, motorbikes, racing cars.